20-410 ribbed black treatment pump with clear pp hood. Dip tube 4"
The first number is the diameter of the container's opening (in mm). The second number refers to the thread/style/depth of the closure's skirt. Dip tubes can be trimmed to fit smaller, shorter containers.
Treatment pumps are the workhorses of the pumping world. They dispense the stuff that other pumps struggle with. If you have a pumping problem stemming from your product formula being too thick, then treatment pumps may well be your solution. They dispense small amounts unlike their cousin the regular pump.